import math, re

x1, y1, x2, y2 = [float(n) for n in re.split(r"\s+", input().strip())]
print("%f" % (math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2)))
 import math, re math re float(n) for n in re.split(r"\s+", input().strip()) for n in re.split(r"\s+", input().strip()) n re.split(r"\s+", input().strip()) re.split re split r"\s+" input().strip() ().strip () input strip for n in re.split(r"\s+", input().strip()) float(n) float n x1, y1, x2, y2 = [float(n) for n in re.split(r"\s+", input().strip())] x1 [float(n) for n in re.split(r"\s+", input().strip())] y1 x2 y2 print("%f" % (math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2))) print "%f" % (math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2)) "%f" math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2) math.sqrt math sqrt (x1 - x2) ** 2 + (y1 - y2) ** 2 (x1 - x2) ** 2 x1 - x2 x1 x2 2 (y1 - y2) ** 2 y1 - y2 y1 y2 2 y1, x2, y2 = [float(n) for n in re.split(r"\s+", input().strip())] [float(n) for n in re.split(r"\s+", input().strip())] y1 x2, y2 = [float(n) for n in re.split(r"\s+", input().strip())] [float(n) for n in re.split(r"\s+", input().strip())] x2 y2 = [float(n) for n in re.split(r"\s+", input().strip())] [float(n) for n in re.split(r"\s+", input().strip())] y2 x1, y1, x2, y2 = [float(n) for n in re.split(r"\s+", input().strip())] [float(n) for n in re.split(r"\s+", input().strip())] x1
import math, re

x1, y1, x2, y2 = [float(n) for n in re.split(r"\s+", input().strip())]
print("%f" % (math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2)))

